Comparative Fecal Microbiota Analysis of Infants With Acute Bronchiolitis Caused or Not Caused by Respiratory Syncytial Virus

• Published in: Frontiers in cellular and infection microbiology Vol. 12; p. 815715
• Main Authors: De Maio, Flavio, Buonsenso, Danilo, Bianco, Delia Mercedes, Giaimo, Martina, Fosso, Bruno, Monzo, Francesca Romana, Sali, Michela, Posteraro, Brunella, Valentini, Piero, Sanguinetti, Maurizio
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 07.03.2022
• Subjects: acute bronchiolitis; Cellular and Infection Microbiology; fecal microbiota; infants; respiratory effort; respiratory syncytial virus; severe illness; fecal microbiota; infants; acute bronchiolitis; severe illness; respiratory effort; respiratory syncytial virus
• ISSN: 2235-2988; 2235-2988
• DOI: 10.3389/fcimb.2022.815715

Bronchiolitis due to respiratory syncytial virus (RSV) or non-RSV agents is a health-menacing lower respiratory tract (LRT) disease of infants. Whereas RSV causes more severe disease than other viral agents may, genus-dominant fecal microbiota profiles have been identified in US hospitalized infants with bronchiolitis. We investigated the fecal microbiota composition of infants admitted to an Italian hospital with acute RSV (25/37 [67.6%]; group I) or non-RSV (12/37 [32.4%]; group II) bronchiolitis, and the relationship of fecal microbiota characteristics with the clinical characteristics of infants. Group I and group II infants differed significantly (24/25 [96.0%] versus 5/12 [41.7%]; P = 0.001) regarding 90% oxygen saturation (SpO 2 ), which is an increased respiratory effort hallmark. Accordingly, impaired feeding in infants from group I was significantly more frequent than in infants from group II (19/25 [76.0%] versus 4/12 [33.3%]; P = 0.04). Conversely, the median (IQR) length of stay was not significantly different between the two groups (seven [3–14] for group I versus five [5–10] for group II; P = 0.11). The 16S ribosomal RNA V3–V4 region amplification of infants’ fecal samples resulted in 299 annotated amplicon sequence variants. Based on alpha- and beta-diversity microbiota downstream analyses, group I and group II infants had similar bacterial communities in their samples. Additionally, comparing infants having <90% SpO 2 ( n = 29) with infants having ≥90% SpO 2 ( n = 8) showed that well-known dominant genera ( Bacteroides , Bifidobacterium , Escherichia / Shigella , and Enterobacter / Veillonella ) were differently, but not significantly ( P = 0.44, P = 0.71, P = 0.98, and P = 0.41, respectively) abundant between the two subgroups. Overall, we showed that, regardless of RSV or non-RSV bronchiolitis etiology, no fecal microbiota-composing bacteria could be associated with the severity of acute bronchiolitis in infants. Larger and longitudinally conducted studies will be necessary to confirm these findings.